Pump pressure hydraulic jarring tool



Nov. 22, 1960 J B DAVIS, SR

PUMP PRESSURE; HYDRAULIC JARRING Toor.

3 Sheets-Sheet 1 Filed Dec. 24, 1958 ATTORNEY J B DAvls, sR 2,961,048

3 Sheets-Sheet 2 PUMP PRESSURE HYDRAULIC JARRING TOOL.

INVENTOR ff a v 5u/5?".

in 'Il` y?, A nf# ATTORNEY Nov. 22, 1960 Filed Deo. 24, 1958 Nov. 22, 1960 J B DAVIS, SR

PUMP PRESSURE HYDRAULIC JARRING TooL 3 Sheets-Sheet 5 Filed Dec. 24, 1958 United States This invention relates to a tool for jarring loose objects which are struck in a well casing or a well bore ot the earth and which cannot be moved by a pulling or pushing force exerted from the top of the well.

A primary object of the present invention is to provide a jarring tool operated by hydraulic pressure and which will eitectively function for intermittently exerting a jarring or impact force on a part of the tool for jarring upwardly or jarring downwardly on an object stuck in a well without exerting an additional strain or force on the drill pipe or tubing.

Another object or" the invention is to provide a jarring tool wherein a constant supply of a liquid under pressure downwardly into the jarring tool will cause the tool to be intermittently driven in either an upward or a downward direction for exerting either an upward or a downjarring force on an object stuck in a well, and wherein, after each jarring stroke, the tool parts will be forced in the opposite direction automatically and re-cocked and thereafter automatically released and driven to eiect another jarring or impact stroke.

Various other objects and advantages of the invention will hereinafter become more fully apparent from the tollowing description of the drawings, illustrating presently preferred embodiments thereof, and wherein:

Figure l is a longitudinal substantially central sectional View of an upper portion of the jarring tool, shown with the parts thereof latched in a retracted posit-ion;

Figure lA is a similar view showing the lower portion of the tool;

Figure 2 is a View, similar to Figure l, but showing the upper half of the tool with the parts thereof in a released and operative position;

Figure 2A is a view of the lower portion of the tool with the parts disposed in the sarne position as in Figure 2;

Figure 3 is a longitudinal substantially central sectional View, partly broken away and on an enlarged scale, of the lower portion of a slightly modified form of the jarring tool;

Figure 4 is a View similar to a portion of Figure 3 but showing a different position of certain of the tool parts;

Figure 5 is an enlarged cross sectional view of the jarring tool, taken substantially along the line 5 5 of Figure l;

Figures 6 and 7 are cross sectional views of the jarring tool, on enlarged scales, taken substantially along planes as indicated by the lines 6 6 and 7 7, respectively, of Figure 1A, and

Figure 8 is a fragmentary side elevational view of a portion of the jarring tool.

Referring more specically to the drawings, and first with reference to Figures l, lA, 2, 2A, and 5 to 8, the jarring tool in its entirety and comprising the invention is designated generally 1li and includes an elongated housing or barrel 11 formed of sections. The upper section 12 of the barrel 11 is elongated md includes an upper i atent l j 2,961,048 Patented Nov. 22, 1960 ICC portion 13 having a bore 14 extending longitudinally therethrough which is provided with an enlarged internally threaded upper end 15 and an enlarged lower end 16. The lower end 16 of the bore is likewise partially threaded for receiving therein a stuting box 17. The upper housing section 12 includes an annular skirt 18 which extends downwardly from the lower end of the upper portion i3 and which is provided with an internally recessed and threaded lower end i9. The skirt 18 is provided with one or more exhaust ports 2G, disposed above and adjacent its threaded portion 19.

The barrel or housing il includes a short section 21 having an upper portion 22 which is solid except for a central bore 23 of the same diameter as the bore le. The upper portion of the periphery of the head 22 is restricted and threaded, as seen at 2d to threadedly engage in the threaded portion 19. The section 22 includes a depending annular apron 25 having an internally enlarged threaded lower portion 26 corresponding to the portion 19. The barrel section 21 is of a length substantially less than that of the upper barrel section 12.

A barrel section 27, of substantially greater length than the barrel section 21, is disposed immediately therebeneath and has an upper end or head 28 provided with a central bore 29, corresponding to the bore 23. The head 28 is also provided with one or more passages 36- extending therethrough and. which are radially spaced from the bore 29. Said head 28 has its upper peripheral portion reduced in diameter and threaded as seen at 31 to threadedly receive the apron portion 25. The annular depending apron or skirt 52 or" the barrel section 27 is of a greater length than the aprons or skirts 1S and Z5 to provide a cylinder, as will hereinafter be described, wd includes an enlarged internally threaded lower end 33, similar to the threaded portions 19 and 26.

The next section 34 of the barrel 11 has a head 35 at its upper end, corresponding to the head Z8, including a central bo-re 36, passages 37 and an externally threaded portion 38. Said portion 38 threadedly engages in the skirt portion 33` for connecting the section 34 to the lower end of the section 2,7. The section 3d includes a short annular skirt 39 having a threaded lower end 4G, similar to the threaded skirt portion 33'.

The next, shorter section 4.1 of the barrel 11 has a head 42 at its upper end provided with a central bore 43 of the same diameter as the bore 36 but having an enlarged upper end to receive a stuliing box 44. The head 42 has an externally threaded upper part d5, similar to the part 38, which is threadedly secured to the skirt portion 4t). The section 41 has a short annular skirt 46 which is provided with an internally threaded lower end 47 which is similar to the skirt portion 4l?. The ski-rt i6 is also provided with one or more exhaust ports 43.

The next lower barrel sect-ion 49 corresponds substantially with the barrel section 25 and has a head 56` at the upper end thereof which is provided with a central bore 51 of the same diameter as the bore 33. he head 50 is externally recessed and threaded as seen at 52 to threadedly tit in the skirt portion 47 and has a depending annular skirt 53. The lower end of the skirt 53 is internally recessed and threaded as seen at 5d.

The next lower barrel section 55 is a duplicate of the barrel section 27 including a head 23 having a central bore 29', passages Sil and a threaded portion 31. The threaded portion 3l' engages threadedly in the skirt portion 54. The skirt 32 of the section 55, the lower part of which -is shown in Figure 1A, has an internally threaded lower end portion 33 which is threadedly connected to the portion 3S of the next lower barrel section 56, which corresponds to the barrel section 34. A head 35 of said barrel section 56 has a central bore 36 and one or more passages 37'. The depending annular skirt 39 of said section 56 has an internally threaded recessed Vlower end 46.

The next section 57 of the barrel 11 includes an elongated head or body 53 having a bore 59 extendingcen- VtrallyV therethrough and of the same diameter as the bore 14, which is provided with a recessed upper end 60 to receive a stufling box 6l. The upper end of the body 53 is externally restricted and threaded as seen at 62 to threadedly engage in the skirt portion 4G. The body 58 has a diametrically extending bore 63 opening outwardly thereof and communicating with the bore 59 to form two outwardly opening exhaust ports. The section 57 includes a short internally threaded skirt 64 which depends from the lower end of the body 58. VThe body 53 has an upper set of radial bores 65 opening outwardly thereof and into the bore 59 and a lower set of corresponding bores 66. rthe bores 65 and 66 are disposed between the annular skirt 64 and the exhaust ports 63. A ball latch 67 is mounted in each upper bore 65 and a ball latch 63 is mounted in each lower bore 66. The outer end of each bore 65 and 66 is closed by a removable plug 69 which threadedly engages therein. A compression spring 79 is mounted in each bore 65 and 66 between the latch ball and plug thereof, whereby saidlatch Aballs 67 and 68 are urged inwardly into the longitudinal bore 59 by the compressed springs 70. The plugs 69 form adjustable spring stops for said springs 7).

The next section 71 of the barrel 11 has a head 72 disposed near the lower end thereof which is provided with a central bore 73 of the same diameter as the bore 59. The bore 73 has an enlarged lower end 74 receiving a stuing box 75, and an annular wall 76 extends upwardly from the head 72 and has an externally restricted and threaded upper end 77 which threadedly engages in the skirt 64. The barrel section 71 has a short internallyV threaded annular ange 7S extending downwardly from the periphery of the head 72.

A bottom section 79 of the barrel 11 is substantially cup shaped and has a bottom wall i provided with a central opening 81 of larger diameter than the bore 73. The section 79 has a cylindrical wall 82 extending upwardly from the bottom 86 and which is provided with an externally restricted threaded upper end 83 which threadedly engages in the flange 7S. The wall 82 is provided with tworlongitudinaliy extending oppositely disposed slots S4 and two shorter circumferentially extending slots 85. The slots 35, one of which is shown in Figure 8; extend'in the same direction from the upper ends of the slots 84, clockwise as illustrated in Figure S. Thus, the slots 85 form angular extensions of the upper ends of the slots 84.

A tubular rod, designated generally 876, extends su-bstantially through and is slidably mounted in the barrel 11 and is disposed axially thereof. The rod 86 is composed of an upper end section 87, a lower end section SS, an intermediate section 89, and two corresponding sections 9i) and 91, each of which sections is tubular from end-to-end thereof, The lower end of the upper section 87 and the upper end of the llower section SS are each internal-ly enlarged and threaded, as seen at 92. Both ends of the intermediate section S9 have similar internally threaded end portions 92. The tubular rod sections 90 and 91 at both ends thereof are externally restricted'and threaded, as seen at 93. The upper end or' the rod section 90 has the portion 93 thereof threadedly engaging in the portion 92 of the rod section 87 and the portions 92 of the intermediate section 89 threadedly engage the adjacent threaded ends 92 of the rod sections 98 and 91. The other lower end 93 of the rod section 91 threadedly engages in the upper Vthreaded portion 92 of the bottom rod section 8S. A spring stop in the form of a dise 94 threadedly engages each ythreaded portion 93 and is clamped to the rod S6 by a threaded connection 92, 93. A piston 95 is slidably mounted on the rod section 9d and has a close fitting sliding engagement in the cylinder 32 of the barrel section 27, and a similar piston 96 is slidablygmounted on the rod section 91 and within the cylinder 32 of the barrel section 55, each of said pistons being disposed for sliding movement between two spring stops 94. A coiled compression spring 97 is disposed between each piston 95 and 96 and the spring stop 94, disposed therebeneath, and a stronger compression spring 98 is disposed above each piston and 96, and between said piston and the spring stop 945 disposed thereabove.

rihe upper portion of the upper rod section S7 extends slidably through the stuing box 17 and into the bore 1.4. Said rod section 87 also extends slidably through the bores 23 and 29 and is provided with an externally restricted portion 99 which forms, in combination with the bore 23, a passage between the chamber 199 of the upper barrel section 12 and the chamber '191 of the barrel section 2i, in one position of the rod S6, as seen in Figure l. The rod section 87 also has ports 162 opening outwardly thereof below the resricted portion 99 and which form communicating passages between the bore 193 of the rod 86 and the chamhier 161, in another position of the rod 36, as seen in Figure 2. The intermediate rod sec-tion 39 has an externally restricted intermediate portion 104 which cornlbines udth the bore 51 Vto form a communicating passage between the chamber 165 of the barrel section 41 and the chamber 166 of the barrel section 49, in one position of the rod S6, as seen in Figure l. Said restricted portion 1% combines with the bore 43 and stufng box 44 to form a communicating passage between the chamber N5 and the chamber 107 of the barrel section 34, in an alternate position of the rod S6, as seen in Figure 2. The rod section 39 has ports 103, above its restricted portion 104, which open into the chamber 167 in a lower position of the rod S6, as seen in Figure 1, and ports E69, disposed below the restricted portion 164, which open into the chamber 106, in a raised position of the rod S6, as seen in Figure 2. The hollow portions of the barrel l11 which communicate with the ends of the cylinders 32 and 32 Von opposite sides of the pis-tons 95 and 96 thereof, respectively, constitute pressure chambers. Y

The bottom rod section S8, near its upper end, has ports opening into the chamber 111 of the barrel section 56, in a lowered position of the rod 86, as seen in Figure 1A. The rod section 38 vhas an externally restricted portion 112, below the ports 11G, which combines with the stuffing boxr611 and a part of the bore 59 to form a passage between the chamber 111 and the exhaust ports 63, in a raised position of the rod S6, as seen in Figure 2A.

Below the restricted portion 112, the rod section 88 has an upper annular groove 113 and a lower annular groove 114. The hall latches 67 seat in the groove 113 and the ball latches 68 seat in the groove 114 for latching the rod 86 in its lower position of Figures l and lA. A nut 115 is threadedly connected to the rod section 88 and moves therewith within the chamber 116 of the barrel section 71, to form an impact member, as will hereinarter be described;

The bore 163 includes a rcs-tricted lower end 117 formed in the lower portion of the rod section 88, the lower end of which is closed and sealed by a threaded plug 118. Said restricted bore portion 117 has ports 119 extending therefrom radially through the rod section 83.

A valve body 120 is disposed slidably in the bottom barrel section 79 and fits slidably on the bottom rod section S3. Said valve member 26, which is annular, has a central recess 121 in its lower end to receive a stuing box 122 which is disposed around a portion of the rod section V88. A sleeve 123 is disposed loosely around the lower portion of the rod section 88 and ex tends slidably through the bottom opening 81 of the barrel section 79. The upper end of the sleeve 123 is externally and internally enlarged and externally threaded to form a nut 124, constituting a part of the stuing box 122, by means of which said sleeve is connected to the valve 120. Screws 125 are threaded radially into the valve 120 and have heads 126 extending outwardly from said valve and which engage slidably in the slots 84 and 85.

A tubular coupling 127 has an enlarged upper end which is threadedly connected as seen at 128 to the outer side of the lower end of the sleeve 123. The coupling 127 has a restricted externally threaded lower'end 129 by means of which it may be threadedly connected to any conventional grappling member, such as the grappling member 130, as seen in Figure 1A.

A tubular coupling 131 has an externally threaded lower end 132 which threadedly engages in the recess 15 of the upper barrel section 12. The coupling 131 has an internally threaded upper end 133 for attachment to the lower end of a handling string, drill pipe or other tubing, not shown. A bore 134 of the coupling 131 forms a communicating passage between the handling string or drill pipe and the bore 14 and bore 103.

Assuming that the jarring tool is to be utilized for loosening and pulling upwardly on an object stuck in a Well, as for example, the liner or sleeve, a part of which is shown in Figure 1A at 13S, with the tool 10 coupled by the coupler 131 to the handling string and with the screw heads 126 engaging the horizontal slots 85, as seen in Figures 1A, 7 and 8, the tool 10 is lowered into the well until the grappler 130 enters the sleeve or liner 135, as seen in Figure 1A. The tool 10 is then turned by the handling string in a desired direction for expanding the gripping elements 136 into gripping engagement with the liner or sleeve 135. When this has been accomplished, an upward pull is exerted on the handling string and tool to make sure that the grappler 130 is secured fast to the liner or sleeve 135. The upward pull on the handling string is then slacked off to approximately equal the weight of the handling string and tool, after which the tool is turned counterclockwise, as seen in Figure 7, for moving the screw heads 126 out of engagement with the horizontal slots S5 and into engagement with the longitudinal slots 84, fcr unlatching the valve 120 from its raised position in the barrel section 79, as seen in Figures lA, 7 and 8. The handling string and tool 10 are then raised relative to the valve 120 and sleeve 123, to cause said valve and sleeve to assume the positions as seen in Figure 2A, relative to the barrel 11 and rod 86, and to put an upward strain or pull on the liner or sleeve 135. When the valve 120 is in its lower position of Figure 2A, said valve closes the discharge ports 119 of the lower bore portion 117. A liquid, such as water, is then pumped downwardly through the handling string, coupling 131 and bore 14 into the upper end of the bore 103. The rod 86 will be disposed in its lowermost position of Figures 1 and 1A, held latched against upward displacement by the latch balls 67 and 68 engaging the grooves 113 and 114. The fluid medium being pumped downwardly under pressure through the bore 103 will escape therefrom through the ports 108 into the chamber 107 and through the passages 37 into the cylinder 32 below the upper piston 95. The Huid also escapes from the bore 103 through the ports 110 into the chamber 111 and through the passages 37 into the cylinder 32' below the piston 96. As the pressure builds up in the cylinders 32 and 32 below the pistons 95 and 96, said pistons are forced upwardly on the rod 86 and within said cylinders for compressing the springs 98 disposed thereabove. When sufficient pressure builds up on the spring stops 94 which engage the upper ends of the springs 98, the rod 86 will be forced upwardly by overcoming the pressure of the latch ball springs 70 for forcing said latch balls out of the grooves 113 and 114. When this occurs the rod 86 will be thrust upwardly with great force by the hydraulic pressure below the pistons and 96 and by the pressure of the compressed springs 98 to cause the hammer or impact member 115 to strike forcibly against the underside or impact surface 137 of the body 58 for jarring the tool 10 upwardly to produce an upward jarring force on the grapple and liner 135.

The rod 86 will then be disposed in its raised position of Figures 2 and 2A. The fluid medium under pressure will then escape from the bore 103 through ports 102 into the chamber 101, which ports are closed by the head 28, when the rod was in its lowered position of Figure 1. The fluid will flow from the chamber 101 through the passages 30' into the cylinder 32 above the piston 95. At the same time, fluid under pressure will escape from the bore 103 through the ports 109 into the chamber 106, which ports are closed by the head 28 when the rod 86 was in its lower position. Fluid from the chamber 106 will ow through the passages 30 into the cylinder 32 above the lower piston 96. As the pressure builds up above the pistons 95 and 96, said pistons will be forced downwardly for compressing the weaker lower springs 97. The fluid below the two pistons will escape from the barrel 11 while the cylinders 32 and 32' are being pressurized above the pistons. As seen in Figure 2, fluid below the upper piston 95 will escape from the cylinder 32 downwardly through the passages 37 and chamber 107, through the passage formed by the restricted rod portion 104, stuing box 44 and bore 43 into the chamber 105, and outwardly of the barrel through the exhaust ports 4S. Fluid beneath the lower piston 96 will pass downwardly through the passages 37' into the chamber 111, through the passage formed by the restricted rod portion 112, upper bore portion 59 and stuffing box 61 to the exhaust ports 63, through which the uid escapes from the barrel 11. While this is occurring the rod 86 is held in a raised position by the upper latch balls 67 engaging the lower groove 114, as seen in Figure 2A. When suicient pressure is built up by the lower springs 97 on the spring stops 94, engaged thereby, the latch balls 67 will be cammed out of the groove 114 and the rod 86 will move downwardly to its lower position of Figures l and 1A for thereby recocking the tool 10, after which the operation previously described will be repeated to cause the rod 86 to be again driven forcibly upward to effect another jarring operation, by the hammer or impact member 115 again moving upwardly and forcibly against the anvil surface 137.

However, after the first upward movement of the rod 86, uid above the pistons 95 and 96 will be expelled from the barrel 11 by upward displacement of said pistons. As seen in Figure l, as the upper piston 95 moves upwardly, fluid will be forced from the upper part of the cylinder 32 through passages 30 into chamber 101 and through the passage formed by the bore 23 and restricted rod portion 99 into the upper chamber 100 from which the uid will escape through the ports 20. At the same time, the fluid above the lower piston 96 will pass upwardly through the passages 30 from the cylinder 32 into the chamber 106 and through the passage formed bv the restricted rod portion 104 and bore 51 into the chamber 105, from which chamber the fluid will escape from the barrel 11 through the exhaust ports 48.

This intermittent jarring action caused bv the intermittent reciprocating movement of the rod 86 will continue as long as a sufiicient fluid pressure exists in the bore 103. After the stuck object has been jarred loose in this manner, the handling string is slacked otr' to cause the tool 10 to slide downwardly relative to the valve 120 and sleeve 123, after which the handlin"7 string and tool are turned counterclorkwise, as seen in Figure 7, to position the screw heads 126 in engagement with the horizontal slots 85 to thereby re-latch the valve 120 and sleeve 123 in the raised positions of said parts, as seen in Figure 1A. When the valve 120 is thus latched in a raised position the ports 119 are open so that the fluid medium can neeipae 7 escape therethroughrfrom the bore 103 andfromthe han'- dling string, the fluid owing 'into the'sle'eve VV'123 and escaping therefrom through the coupling 127 and grapple V130, Vso that the iluid will not have to be lifted from the well with the tool 10. Y

As previously stated, any number 'of spring Vlatch balls 67 and 68 and their associated parts may be utilized for varying the amount of pressure requiredlto cam the latch balls out-oi:` the grooves 113 and 114, so that the amount of jarring force exerted by, the tool on each upward stroke of the rod S6 can be varied. 4This 'can aiso be accomplished by increasing the pressure of the springs 7G. In addition, additional pistons may be provided for further increasing the 'upward force imparted 4to the rod 86.

Figures 3 and 4 illustrate a slight variation in connection with the lower portion of the tool, and where-in the remainder ofthe tool is identical with the tool as previously described. The jarring tool 16a differs from the to'ol V10 in that'the upper and lower latch ball receivinggroo'ves 113' and 114', respectively, are disposed lower-.than the grooves H3 and 114, and thus nearer the impact orjha'mrner member 115. in addition, the upper groove i113' has a downwardly inclined annular bottom edge 140. The 'tapered portion 41 connecting the bore 03' to the bore 117 of the bottom rod section S8 forms 'a valve seat for a small ball valve 142 which is dropped through the handlingstiing and through the rodbore 193 into engagement with the seat 141 for Vsealing the ports 119.

With this structural change, the tool a can be used as a hammer for exerting a jarring action in a downward direction.V A head orgrap'ple, not shwn, off any suitable construction can be attached -to the lowerV end of the coupling 127' for engaging a piling or otherrobject to be riven downwardly. The valve 120 is maintained latched in its raised position, as seen in Figures 3 and 4.

The rod 86', in 'its-raised position of Figure 3 is .in the same position relative to the tool barrel :11' as is the rod 86 relative to the tool barrel 11, as illustrated -in Figures 2 and 2A. Thus, the uid escapes from the :bore v103' above the pistons, not shown, until sufcient pressure is exerted thereby to force the rod 86 downwardly by the latch balls 67 and 63 being cammed out of the grooves 113 and 114', so that the rod r86 will be driven forcibly downward. When this occurs, the hammer l115' moves downwardly from its raised position of Figure V3 kand forcibly strikes the upwardly facing anvil surface v14,3 for`driving the tool barrel 11', valve 120', sleeve 123 and cfoupling 127' forcibly downward to exert an impact or jarring stroke. When the hammer 115 is in engagement with'tne anvil surface 143' the upper groove' 113 is disposed to receive the lower latch balls 68 and the rod 86 is in its lowerrnost position, so that the fluid under pressure can be supplied to the undersides of the pistons for forcing the rod Y36 rupwardly* and` back tov its raised, cocked position of Figure 3, from its lower position- Yof Figure 4. The inclined surface i4@ of the groove 113 allows the lower latch balls 68' to be more readily cammed outrof the upper `groove 113', so that less Ypressure is required to raisethe rod S6' .back to its elevated, cocked position. K. n

A well casing, not shown, in which the .tool 10a is disposed can be sealed oit and a liquid pumped into the casing to flow into the bore 117 through the port 119 to unseat and force the valve 142 out of the bore 103 and out of a drill pipe or the like, not shown, to which the tool lila is connected-so that the tool 10a and drill pipe can Vbe drained through the ports 119', before removal from the well. In view of the detailed description of the tool 10, a furtherl description of the tool 10a is considered `unnecessary.

' Various other modifications and changes are contemplatedV and may obviously be resorted to, without departing fromV the function or scope of the invention as here,` inafter deined by the appended claims.

Icl'aim as'my invention; l 1. A jarring tool comprising an elongated barrel forming a tool body, a hollowV rod mounted for longitudinal sliding movement in said barrel, means attached t'o an upper end of said barrel for supporting the barrel and through which a fluid medium under pressure is supplied to said hollow rod, at least one piston having a close fitlting sliding engagement on a part of said r'cd and a close fitting sliding engagement in a part of said barrel, compression springs carried by said rod and between which said piston is yieldably supported, said barrel having pressure chambers on opposite sides of the piston, said barrel and rod having co-acting parts forming separate valve means for supplying kthe duid medium underV pressure to said pressure chambers from the -rod and separate valve means for exhausting the fluid medium from ysaid pressure chambers,means controlling the operation of the supply valve means and the exhaust valve means whereby as pressure is exhausted from one of the `pressurechambers the other pressure chamber is pressurized for causing a reciprocating movement of Vsaid rod longitudinally of the barrel, mean releasably latching vthe rod to the `barrel at the extremities of movement of said rod to effect an intermittent reciproca-ting movement o'f the rod, a hammer fixed to a part of said rod, said barrel having an impact surface disposed to be struck by the hammer as the rod moves in one direction on the impact strokethereof for effecting a longitudinal jarring movement of the tool, and means connected tothe lower end o said tool for connectingthe tool to an object to be moved by thejarring movements of the tool. A i Y 2. A jarring tool as in claim l, said latch means comprising spring pressed ylatch membersV mounted in the barrel and urged radially toward the rod, and grooves disposed in the periphery of the rod in which said latch-members releasably engage, -said grooves Vbeing disposed whereby all of the latch members are in engagement therewith to resist movement of the rod .on the imp-act stroke and whereby only a portion of the latch members are in engagement with the grooves to resist movement of the rod on the return stroke, so-that a greater fluid pressure 'is required against the piston to initiate movement of the rod on the impact stroke. Y y, p l

3. A jarring tool as in Lclaim 2, one o-f said compression springs being stronger than the other compression spring and being disposed to4 be compressed bythe piston when displaced in a direction for moving the rod on the impact stroke thereof whereby said stronger compression spring will cooperate with the fluid pressure exerted on the piston for driving the rod .on the Vimpact stroke thereof.

4. A jarring toolfas in claim l, said barrel being formed Yof a plurality of detachably connected sections each including a cylindrical wall portion and at least one transverse wall having a central bore through which the rod slidably extends. Y y Y 5. A jarring tolol 4as in claim 4, said exhaust valve means including longitudinally spaced ports and externally recessed portions formed in said rod-and cooperating with said bores of the barrel sections to permit selective movement of the duid medium under pressure from the rod into and /thnugh the pressure chambers.

6. A jarring tool -as `in claim 5, said rod comprising a plurality of threadedly connected sections, a pair of spring stops detachably secured immovably to end portions of one of said sections, said piston being slidabl-y disposed on said rod section, and said compression springs being disposed between the piston and saidy spring stops.

` 7; A jarring tool asin claim 1, said rod having an exhaust port adjacent a lower end thereof for draining the rod, a valve s-lidably disposed on the lower part of the rod vvand within a lower portion of the barrel for sealing said exhaust port o'f the rod in an operative position of the tool, and means for releas-ably latching said valve to the barrel in an open position of the valve.

, 8. A jarring tool as in claim 7, and means connecting said valve to said means for connecting the tool to an ob ject to be moved for movement of the barrel and rod relative to the valve.

9. A jarring tool as in claim 1, the bore of said hollow rod having a restriction near its lower end forming an upwardly facing valve seat, said rod having a port opening outwardly thereof and into the bore below the valve seat, and a valve engaging said valve seat for closing the bore, said valve being forced upwardly out lof the rod by a reverse flow of liquid through said port into the bore beneath the valve seat.

10` A jarring tool comprising an elongated barrel forming `a tool body, a hollow rod slidably disposed in and extending longitudinally of the barrel, means for closing and sealing the lower end of the bore of said rod, means connected to an upper end of the barrel for exerting a force lengthwise of the tool and for supplying `a uid medium under pressure to the bore of the rod, a piston carried by said rod and slidably disposed in a part of the barrel, separate means for releasing the uid medium under pressure into the barrel from the rod on opposite sides of the piston, separate means for exhausting the uid medium from the barrel on opposite sides of the piston, means controlling the operation of the release means and exhaust means whereby as pressure is exhausted from the barrel on one side of the piston the barrel is pressurized on the opposite side of the piston for electing a reciproeating movement of the rod in the barrel, latch means for latching the rod to the barrel at one extremity fof movement of the rod for eecting `an intermittent reciprocating movement of the rod in the barrel and a rapid movement olf the rod in one direction relative to the barrel, a h'ammer carried by and movable with said rod, and said barrel having fan anvil portion disposed to "be forcibly struck by the hammer when the rod is moved in said aforementioned direction of rapid movement,

11. A jarring tool as in claim 10, and means for coupling the other lower end of the tool to an object to be moved by an intermittent jarring movement of the tool ca sed by the hammer striking said anvil portion.

12. A jarring tool as in claim 11, said piston being mounted for sliding movement on a portion of said rod, a compression spring supported by said rod bearing against one side of the piston and disposed to be compressed by movement of the piston relative to the rod while the rod is held latched to the barrel whereby the compressed spring cooperates with the Huid pressure exerted on the piston for forcibly driving the hammer against the anvil surface when the rod is forcibly unllatcherl from the barrel.

References Cited in the file of this patent UNITED STATES PATENTS 2,250,775 Rice July 29, 1941 2,671,640 Baker Mar. 9, 1954 2,690,226 Comstock Sept. 28, 1954 2,732,901 Davis Jan. 31, 1956 

